HSODA-129 "Look at my big, grown nipples!" Sunao Kui, a silent woman obsessed with nipple stimulation, has grown perversely large nipples with sensitivity that surpasses her clitoris.

One day during his college years, a man wakes up in the room of his senior, Kui, after passing out at a drinking party. There, he discovers Kui’s secret hobby—"nipple training via masturbation"—and enters into a relationship with her that must remain strictly confidential. Time passes, and the man lands a job at the same company as Kui; the two continue their secret affair just as before. Her nipples, trained to be even more sensitive than in their college days, have become a source of pleasure surpassing even the clitoris! Furthermore, Kui applies this same training to the man's nipples. He is driven wild by a sensation completely distinct from the pleasure of a cock—and witnessing his reaction turns her on. This is the ultimate culmination of a woman's astonishing record of perversely dedicated nipple training.